Methods of dynamic mechanical analysis using nuclear magnetic resonance
Abstract
Method of dynamic mechanical analysis of a sample including providing a magnet with a constant gradient where at least a portion of the sample is in the constant gradient, inducing a vibration in the sample in the direction of the constant gradient, the vibration comprising a vibration waveform and a vibration period, generating an NMR pulse sequence comprising at least two pulses with a delay between the pulses, acquiring echos from the pulse sequence at multiple points along the vibration period, measuring the phase of the NMR signal at each of the acquired echos, using the phase of the NMR signal to measure the velocity of the vibration at the multiple points where the echos are acquired, using the velocity measurements to acquire a velocity waveform, and using the velocity waveform and processing the velocity waveform to extract the loss angle and the magnitude of the dynamic modulus of the sample.
Claims
exact text as granted — not AI-modifiedWe claim:
1. A method of dynamic mechanical analysis of a sample comprising:
providing a magnet to generate a constant gradient where at least a portion of the sample is in the constant gradient;
inducing a vibration in the sample in the direction of the constant magnetic field gradient, the vibration comprising a vibration waveform and a vibration period;
generating an nuclear magnetic resonance (NMR) pulse sequence comprising at least two pulses with a delay between the pulses;
acquiring echos from the pulse sequence at multiple points along the vibration period;
measuring the phase of the NMR signal at each of the acquired echos;
using the phase of the NMR signal to measure the velocity of the vibration at the multiple points where the echos are acquired;
using the velocity measurements to acquire a velocity waveform; and
using the velocity waveform and processing the velocity waveform to extract the loss angle and the magnitude of the dynamic modulus of the sample.
2. The method of claim 1 , wherein the vibration waveform is an sinusoidal waveform.
3. The method of claim 1 , wherein the vibration waveform is a complex waveform.
4. The method of claim 1 , wherein the pulse sequence is synchronized with the vibration.
5. The method of claim 1 , wherein the echo time is shorter than the vibration period.
6. The method of claim 1 , wherein the magnet is a unilateral magnet.
7. The method of claim 1 , wherein the magnet is a portable magnet.
8. The method of claim 1 , wherein the phase is measured at the peak of each echo.
9. The method of claim 1 , wherein the motion induced phase at the first echo is determined by using the equation:
ϕ
(
2
τ
)
=
-
ϕ
(
τ
)
+
γ
Gv
∫
τ
2
τ
tdt
=
γ
Gvτ
2
where y is the gyromagnetic ratio, G is the magnetic field gradient and v is the average velocity in the slice over the echo time.
10. The method of claim 1 , wherein the sample is a human tissue sample.
11. The method of claim 1 , wherein the sample is a polymer.
12. The method of claim 1 , wherein the sample is a food.Join the waitlist — get patent alerts
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